Pine beetle impact on carbon balance as important as British Columbia fossil-fuel use

Animals & insects have big impact on the carbon cycle

Not only is climate change contributing to things like Spruce beetle outbreaks (by changing weather patterns and causing droughts, etc), but those outbreaks can, in turn, have a big impact on the carbon cycle. That's what researchers at Yale have concluded after studying the impact of animal and insect populations on the carbon cycle, and how current models don't fully take those factors into account.

While models typically take into account how plants and microbes affect the carbon cycle, they often underestimate how much animals can indirectly alter the absorption, release, or transport of carbon within an ecosystem, says Oswald Schmitz, the Oastler Professor of Population and Community Ecology at F&ES and lead author of the paper. [...]

In one case, an unprecedented loss of trees triggered by the pine beetle outbreak in western North America has decreased the net carbon balance on a scale comparable to British Columbia's current fossil fuel emissions

That's just one regional outbreak (though a large one)! There are all kinds of large changes to ecosystems caused by animal and insects... Add them all together and you get something that should definitely be significant.

And in East Africa, scientists found that a decline in wildebeest populations in the Serengeti-Mara grassland-savanna system decades ago allowed organic matter to accumulate, which eventually led to about 80 percent of the ecosystem to burn annually, releasing carbon from the plants and the soil, before populations recovered in recent years.

"These are examples where the animals' largest effects are not direct ones," Schmitz says. "But because of their presence they mitigate or mediate ecosystem processes that then can have these ramifying effects."

What can be done? Well, restoring some of the natural equilibriums that have been lost could potentially help.

For example, in the Arctic, where about 500 gigatons of carbon is stored in permafrost, large grazing mammals like caribou and muskoxen can help maintain the grasslands that have a high albedo and thus reflect more solar energy. In addition, by trampling the ground these herds can actually help reduce the rate of permafrost thaw, researchers say.

"It's almost an argument for rewilding places to make sure that the natural balance of predators and prey are there," Schmitz says. "We're not saying that managing animals will offset these carbon emissions. What we're trying to say is the numbers are of a scale where it is worthwhile to start thinking about how animals could be managed to accomplish that."